1. Field of the Invention
In general, the present invention relates to systems that are used to automatically keep score in a game, such as tennis, that is played on a court with a bisecting net. More particularly, the present invention relates to optical systems that are capable of determining where a ball, shuttlecock, or similar sports projectile strikes the court.
2. Prior Art Description
Many games, such as tennis, volleyball, and badminton, are played on courts that are bisected into two halves by a central net. In all such games, it is the object of the game to propel a ball or shuttlecock over the net and within bounds without allotting an opponent to make a return. When played at a professional level, such games are monitored by one or more umpires. However, in most instances, such games are played for recreation by amateurs. As such, the games are not refereed and the players make their own calls.
Although games like tennis are often played for recreation, that does not mean that the games are not played competitively. In many games, winning and losing matters greatly to the players. Furthermore, making point rulings during the game is often a judgment call where players can disagree. As a consequence, points scored during a game can be contentious. This can lead to player frustration and take way from the fun of playing the game.
It is not practical for recreational players to hire umpires to judge a game. As such, contentious calls are accepted as part of playing the game. An alternative to using real umpires and line judges is to use an automated system. In the prior art, automated systems have been developed that are used to judge points with machine precision. Such systems typically monitor the various bounds of the court with cameras or contact sensors. The data collected by the cameras is analyzed to determine if certain play shots were either in bounds or out of bounds. Such prior art automated systems are exemplified by U.S. Pat. No. 4,664,376 to Gray, U.S. Pat. No. 5,553,860 to Zelikovich, and U.S. Pat. No. 5,800,292 to Brace.
In the prior art, there are more sophisticated automated systems that can not only determine if a shot lands in bounds, but can track a shot no matter where it lands within the court. Such systems typically use multiple arrays of high-speed cameras positioned around the court, so that the position of each shot can be triangulated and tracked. Such systems are exemplified in the prior art by U.S. Pat. No. 5,059,944 to Carmona, U.S. Pat. No. 5,138,322 to Nuttall, U.S. Pat. No. 6,024,658 to Marshall, and U.S. Pat. No. 5,489,886 to Wexler. The advantage of such systems is that they let a player visualize where their shots are landing. This information is useful to players and coaches.
A disadvantage presented by all automated officiating systems in the prior art is that the systems are prohibitively expensive and complex. Systems that use contact sensors require that specialized courts be constructed. Systems that use multiple arrays of high-speed cameras require large capital outlays and extensive calibration by trained technicians. The result is that the costs become so prohibitive, that such systems are only justified at the professional level. Such systems, therefore, are not practical for use on courts utilized by recreational players.
A need therefore exists for an automated officiating system that is practical for use by recreational players, wherein the automated officiating system is inexpensive, easy to install, easy to operate, and easy to maintain. These needs are met by the present invention as described and claimed below.